Such capillary tubelets are thin glass tubes, closed at one end with sealing putty, which are filled with blood and are placed horizontally into receiving clips in a disk of a centrifuge. After centrifuging, it is possible to read off the ratio of erythrocytes to plasma on the basis of the layering in the capillary tubelet.
Such centrifuging devices using a horizontal rotor disk are known per se. In a known device the rotor disk forms a circumferential edge with a layer of rubber on the inside. A plurality of the capillary or hematocrit tubelets are fastened horizontally in receivers on the rotor disk and are pointing outwardly in the form of a star, the hematocrit tubelets with their ends closed by sealing putty being supported during centrifuging against the raised rubber edge of the rotor disk.
In a known device for centrifuging in accordance with German Patent DE-PS No. 30 13 122 a read-off device is additionally disposed on the rotor disk for reading off the exact height of the erythrocyte column by means of a magnifying glass from a scale disposed above the hematocrit tubelets after the rotor has stopped. Prior to this the rotor disk is fixed by means of a clamping device and the scale is calibrated by moving a read-off disk by means of an eccentric.
Such centrifuge devices do not have a separate protective device for the hematocrit tubelets, because of which the thin glass capillaries sometimes can break during the centrifuging. Glass splinters may disadvantageously soil the centrifuge disk or damage adjacent tubelets. Furthermore, the contents of the tubelets may exit in the form of an aerosol from the lid of the centrifuge, which is not pressure-sealed, because of which there is the danger of infection of the user, in particular in view of the danger of AIDS infection.
The steps, known per se, of pressure-sealing the light rotor by means of a hood and locking it are expensive in materials and money and multiply the cost of the apparatus.